I agree with your premise that determining the print date of most post-1955 photographs by objective testing is beyond our capabilities. From my perspective as an art conservator with a special interest in the material history of photography, I think our present situation is both better and worse than you describe and I appreciate the opportunity to comment on the current state of research.

Bad news first. It is a fact that dating any 20th-century print (pre- or post-1955) is problematic. While we have recently discovered components, such as optical brighteners and certain type of papermaking fibers that only turn up in photographs made after 1955, we still have a difficult time dating prints that lack these "red flag" components. For example, current research shows that every photographic paper made from the early 1930s to the mid 1950s contains softwood bleached sulfite pulp and lacks optical brightening agents. By the late fifties things began to change as new papermaking fibers came into use and brighteners were added to baryta coatings and base papers. However, not all photographic paper brought to market after the 1950s contain the newer papermaking fibers or brighteners. Based on these criteria alone, many prints made after 1955 to the present are absolutely consistent with papers manufactured over 70 years ago. This means, of course, that recent high profile authenticity scandals probably would not have been detectable through objective testing if the questioned prints were on more carefully selected contemporary paper. Complicating the picture are the facts that brighteners can be "extinguished" and that very old unexposed paper can be used to make very nice prints. Sophisticated efforts to intentionally misrepresent the origins of photographs, from any period, will always pose problems. The application of digital imaging techniques is one more tool along these lines. Therefore, while I understand your rationale for using 1955 as benchmark date, I want to emphasize that we need to do much more work to understand the material history of 20th-century photography in its entirety.

The good news is that this work is underway. Though progress is slow, the field of photograph conservation is developing tools to characterize photographs through objective analysis and is gradually applying these tools to reference collections of photographic paper. My own growing reference collection contains over 1,600 dated samples of photographic paper identified by manufacturer, brand and surface finish. With time I am hopeful that a partnership of cultural institutions will perform a range of tests on this and other collections.

Another sign of progress is that collecting institutions and galleries have begun to amass technical information on the materials and techniques used by contemporary artists. In large part, this information is generated by artist interviews and questionnaires. Whenever possible, these efforts should be applied to contemporary photographers as well. From the standpoint of the marketplace, the anticipated payoff of these efforts will be the establishment of a firm baseline comprised of multiple criteria that can be compared to photographic prints of unknown or questioned origin. In a larger context, this is exactly the type of materials-based research that has been applied for decades to other artistic media (paintings, sculpture, works on paper), with a tremendous benefit to art history and preservation. At the moment there is more concrete information on Rembrandt's etching papers than there is on the papers used by Man Ray, Weston, Lange and others. Eventually photography will catch up, and the technical, aesthetic and practical criteria that shaped a photographer's choice of paper during a specific time period or for printing a particular negative will be available to scholars for analysis and interpretation.

We have gained a lot of ground over the course of the past few years. When it comes to dating photographs we have tools, techniques and reference collections that were not available even two years ago. Furthermore, within the broader framework of researching the material history of 20th-century photography, goals and the methodologies for achieving those goals are fairly well understood by a small but growing consensus of conservators, conservation scientists, curators and collectors.

Realistically, however, this work is proceeding slowly and conclusive results applied to the problems identified in your essay should not be expected any time soon. In part, the rate of progress is simply a function of the incremental, methodical and multidisciplinary nature of the inquiry. In greater part is the fact that the approach to the problem is generally reactive. Though attention can be white hot in the context of an authenticity scandal, focus and resources gradually get shifted back to business as usual. There is no centralized entity to coordinate and sustain effort and no real funding, meaning the rate of progress and the dissemination of information will remain somewhat haphazard, inefficient and slow.

In the end, determining the origin and date of a photographic print will always have meaning. The discipline of art conservation places tremendous value on expanding knowledge of the materials and techniques used to create artistic and cultural objects. Within the field of conservation, work to understand materials and techniques used by photographers will continue and this work will always have great relevance if only from the standpoint of furthering the preservation of the medium. Whether this information has relevance to the marketplace, especially when it comes to determining value of pre- or post-1955 prints is an open question and best left to your colleagues and clients. However, it seems a given that objects of known origin will always be more desirable than objects of unknown or ambiguous origin.

Paul Messier, Conservator of Photographs, Works on Paper and Electronic Media,

Boston Art Conservation

Do not dismiss the value of old-fashioned connoisseurship. There are real, tangible differences in the look and feel of prints from 1955 and 1975, say, even if both fluoresce under UV light. If you hold a vintage Robert Frank from "The Americans" next to a '70s print, the differences in the warmth of the highlights is obvious; you'd even choose different shades of mats to put them in. Incipient oxidation in the areas of greater silver density is a good indicator of an older print.

And there are some brand-specific indicators as well; for instance, if the Agfa logo on the back of the photo is followed by the subtype, as in "Agfa Brovira," it's an older print.

In the frequent case that the photograph is mounted there are, of course, more signs to look for: is it mounted on crumbly old pressboard or on gleaming white acid-free stock? Look at the edges of the mounts. Crescent board was big in the '60s (from Ansel Adams to Magnum photographers), while the '70s were the beginning of the acid-free era in mounts.

Michael P. Mattis, Collector

The problem you raise--that it is impossible to prove that prints are vintage that were produced after 1955--is very troubling. However, I think the answer is not--as you suggest--that we should eliminate the classification of "vintage" for anything produced after 1955. That would enable photographers and their families to produce and flood the market with an unlimited number of prints of images made 40 or 50 years earlier. It would give equal status to truly vintage prints and prints known to have been produced in the 1990s.

My recommendation would be to do the best we can--which is probably to continue what we are now doing but to give greater recognition to the uncertainty.

You suggest reliance on "connoisseurship" of collectors, dealers, and museum personnel; and that is, I think, the first line of defense. I do not have it but have been greatly aided by connoisseurs who are able to date prints on the basis of papers used, stamps, and other means known best to true connoisseurs. Dealer-connoisseurs agreed that many prints offered by Phillips in New York as vintage in the most recent auctions in New York simply were not. I am impressed that these connoisseurs knew and agreed.

A leading museum conservator taught me that just turning the print over and seeing whether the back has become slightly yellow with age can be a useful, if sub-connoisseur, source of reassurance.

Provenance also helps, but I have become very suspicious of certifications by children of famous photographers. Those heirs have too great an economic stake in declaring certain prints, which they own, to be vintage.

I have found that simply asking the dealer, "Why do you think it is vintage?" can be a good question. Sometimes the answer is a convincing provenance. Sometimes it is a revealing, "The person I got it from said it was 'vintage.'" The policy of such dealers is, "Don't ask, don't tell." We need to ask.

Paul Sack, Collector

(Editor's note: Michael and Paul both raise good points. For the record, I was not suggesting anything specific, but I felt that by raising the issue the larger photography community could all try to seek solutions to it, so that no one is taken advantage of and collectors are not turned off because they bought images that were not what they seem. Education is an important component for any expensive obsession, such as our mutual love of photography.

Early photos are easier to detect, and there are several good tests to backup the visual examination. For instance, it was pretty clear on the Helen Levitts in the Seagram's sale, because true vintage prints would be late 1930s and 1940s, in other words pre-1955. The problem of vintage character becomes a bit more difficult when the original image was made in the 1960s or 1970s, when there may not yet be a definitive test for age and there may be few visual cues and those cues may not be as conclusive as one may think.

While visual cues are certainly a starting place, they can sometimes be misleading. Yellowing of the back of a print or even silvering in shadow areas comes from many factors (largely the components of the paper, chemistry, and its storage environment) and may not always be present in still genuine well-washed, well-kept vintage prints made from top papers, but may actually be seen in non-vintage prints that do not share these attributes--especially when the difference between "vintage" and "printed later" images may only be a matter of 10 years. On the other hand, yellowing on the back of a print and silver oxidation can certainly be contributing factors in making a decision on a print. You just have to weigh these factors against the other factors. The late-printed Hine's prints were often "dirtied" on their backs (one of the ways to tell a non-Hine-made print) to simulate age. I am sure there are more sophisticated ways of doing this. I would appreciate conservators to respond to my comments. I would be happy to be proven wrong on these statements. In any case, we need to find ways to support the kind of efforts that Paul Messier indicates are needed. Perhaps AIPAD, the auction houses and collector groups will help to fund these efforts. It would be great if some sort of consortium of conservation resources was put together to address this issue so that funds could be funneled to support these efforts without overlap.)

Often a vintage print and a later print are quite different, even post 1955. The distinction can be important.

Looking to the future, we might as well be diligent in our current recording practices for posterity. Of course honesty will remain a problem. But in the past print dates were not often recorded because the importance of recording them was not recognized. Now, doesn't having prints without dates seem a bit neglectful? A print is an object, and like a painting, might as well have a date.

Candace Perich, Gallery Owner

There have been a number of occasions where I've visited galleries, been seriously interested in buying, and asked questions, such as: Did the photographer print this? And how do you know? What paper is it printed on? If it was digitally manipulated/printed, did a company do it? If so, what is the name of the company?

My questions were met with a dismissive attitude as if I had the cheek to ask. Fine. No answer, no buy!

Something really should be done, and the time to do it is now. Imagine the company who prints Gursky's stuff. What the value of their hard drives must be? They could just print off what they like.

Many would think fingerprints and legal documentation over the top, but when you think it through, it is where things will have to go if anyone is to have confidence--especially at this time. If a young unknown photographer goes to a lab and asks them to sign a legal statement agreeing not to print any photographs without his/her instructions, the lab would just laugh at them, but imagine, what if that photographer then won the Citibank award--as was the case with Van Meene and Gursky--and they become sought-after photographers?

I am pretty sure all this is going to happen. I know of very few photographers who process and print their own stuff. They produce digital files and make ink jet prints at home or take the file to a lab for a chromogenic print. And some don't even value their own work.

Chris Kargotis, Photographer, London

I do not believe we have ever met, although I have read so many of your newsletters that I feel as if we had.

A thought on issue #57 and the "vintage print" business. It is, of course, a dumb issue. The larger issue is, as you note, who printed it? There have been changes in the papers, far more than in the chemistry, that affect the "look" of the print (ask Paul Caponigro about this). But they affect how the image "looks" far less than what the maker might do in the darkroom.

Compare early and late Brandts, etc. It is only among those not particularly concerned with the fine print that these silly discussions occur--Sommer, Caponigro and photographers of their ilk have spent so much time on each print that minor issues of chemistry become just that: minor. There are so many errors in auction catalogues, museum wall labels (the recent Guggenheim "Moving Pictures" exhibition appeared to set a record in misinformation).

Color photography is a good place to start; there is no such thing as a contemporary "C" print. See the R. Hirsch book "Exploring Color Photography" for a sound explanation on this and a much deeper one in Wilhelm. There are no longer any Cibachrome prints, they are Ilfochrome. This is not nit picking. If future conservationists are to have any chance at saving fading images, they need to at least have accurate records of what materials were used. The auction catalogs will be useless. One hopes that our museums registrars are doing a better job.